Various types of automatic window blind devices have long been known in the prior art. Use and sometimes evolution of such devices have often taught a lack or durability and a lack of automation. Worm gear driven window systems are especially prone to failure, whether human actuated or electrically actuated. One need of automatic window blind apparatus is modular construction wherein various parts are easily replaceable and neither the entire apparatus nor any part yields what is commonly referred to as a throw-away apparatus. Modularity could also provide for variation in sizing of an automatic window blind. As noted, durability is extremely important. Further, a need exists for automatic window blinds that operate by electronic sensing lighting conditions. For example, a sunlight sensing window blind that reacts to light intensity, in opening partially, fully, and closing would be of great convenience. Such window blinds would also add security to a structure by closing at night, therein limiting visual access to a home or office that often invites invasion. Allowing light access during the day, and even limiting intense light could provide utility cost savings and natural light. Providing solar power with battery backup could offer further savings and limit wiring costs as well as providing light from solar generated and stored power. The present automatic window blind system provides these advantages.